During 2020-2021, many hockey leagues (including NHL feeder leagues) had shortened seasons or no season due to the restrictions on play caused by the COVID-19 pandemic. Some players experiencing restrictions on play in played in other leagues or tournaments during the 2021-2022 season. Others did not play any league/tournament games during the 2020-2021 season. This poses the question of whether not playing games during the 2020-2021 COVID season negatively impacted player development (or caused players to get worse). To answer this question, we will examine data from the Ontario Hockey League, which did not play any games during the 2020-2021 season. Some players from this league chose to play in other leagues or tournaments while others did not.
Wrangling:
Filtering:
2019-2020 (“pre-COVID”) and 2021-2022 (“post-COVID”) seasons
league == OHL
Only players who played in the OHL during both pre- and post-COVID seasons
Variables added:
points per game per season (combined if a player played for multiple teams in a season)
games played per season (combined if a player played for multiple teams in a season)
treatment (i.e. whether a player played more than 10 games during the COVID season)
age (approximately the oldest a player was in a given season)
player quality approximated by ppg in pre-COVID season
whether a player was drafted (not totally up to date)
check if explanatory variables are correlated with each other and response.
## [1] 219
## [1] 219
##
## Call:
## lm(formula = ppg_total ~ position, data = ohl_filtered)
##
## Residuals:
## Min 1Q Median 3Q Max
## -0.59399 -0.23754 -0.05861 0.21153 1.22954
##
## Coefficients:
## Estimate Std. Error t value Pr(>|t|)
## (Intercept) 0.32913 0.02782 11.832 < 2e-16 ***
## positionF 0.26486 0.03491 7.586 2.01e-13 ***
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## Residual standard error: 0.3518 on 436 degrees of freedom
## Multiple R-squared: 0.1166, Adjusted R-squared: 0.1146
## F-statistic: 57.55 on 1 and 436 DF, p-value: 2.012e-13
#### Player quality
##
## 16 17 18 19 20 21
## 37 87 105 114 68 27
##
## Call:
## lm(formula = log(ppg_total) ~ treatment + season + position +
## plyr_quality + age, data = filter(ohl_filtered, ppg_total !=
## 0))
##
## Residuals:
## Min 1Q Median 3Q Max
## -1.99539 -0.22503 0.05779 0.23836 1.29327
##
## Coefficients:
## Estimate Std. Error t value Pr(>|t|)
## (Intercept) -1.64116 0.44559 -3.683 0.000261 ***
## treatmentPlayed -0.04555 0.06053 -0.753 0.452164
## season2021-2022 0.73022 0.06647 10.986 < 2e-16 ***
## positionF 0.20241 0.04949 4.090 5.19e-05 ***
## plyr_quality 2.02727 0.09688 20.925 < 2e-16 ***
## age -0.02819 0.02569 -1.097 0.273142
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## Residual standard error: 0.4443 on 413 degrees of freedom
## Multiple R-squared: 0.6902, Adjusted R-squared: 0.6864
## F-statistic: 184 on 5 and 413 DF, p-value: < 2.2e-16
##
## Call:
## lm(formula = ppg_total ~ treatment * position * season * plyr_quality *
## age * drafted, data = ohl_filtered)
##
## Residuals:
## Min 1Q Median 3Q Max
## -0.54455 -0.02995 0.00000 0.00000 0.71995
##
## Coefficients: (2 not defined because of singularities)
## Estimate
## (Intercept) 2.506e-14
## treatmentPlayed -4.546e-12
## positionF -8.059e-13
## season2021-2022 2.159e+00
## plyr_quality 1.000e+00
## age 4.332e-15
## draftedTRUE -1.151e-10
## treatmentPlayed:positionF 1.732e-11
## treatmentPlayed:season2021-2022 -1.551e+00
## positionF:season2021-2022 3.400e-02
## treatmentPlayed:plyr_quality 2.977e-11
## positionF:plyr_quality 7.357e-12
## season2021-2022:plyr_quality -4.543e+00
## treatmentPlayed:age 2.180e-13
## positionF:age 4.440e-14
## season2021-2022:age -1.009e-01
## plyr_quality:age 3.535e-13
## treatmentPlayed:draftedTRUE -3.032e-10
## positionF:draftedTRUE 1.169e-10
## season2021-2022:draftedTRUE 3.133e+01
## plyr_quality:draftedTRUE 7.776e-10
## age:draftedTRUE 6.788e-12
## treatmentPlayed:positionF:season2021-2022 8.137e+00
## treatmentPlayed:positionF:plyr_quality -5.105e-11
## treatmentPlayed:season2021-2022:plyr_quality -3.424e+00
## positionF:season2021-2022:plyr_quality 2.565e+00
## treatmentPlayed:positionF:age -9.966e-13
## treatmentPlayed:season2021-2022:age 7.446e-02
## positionF:season2021-2022:age 3.989e-03
## treatmentPlayed:plyr_quality:age -1.632e-12
## positionF:plyr_quality:age -3.969e-13
## season2021-2022:plyr_quality:age 2.270e-01
## treatmentPlayed:positionF:draftedTRUE 2.906e-10
## treatmentPlayed:season2021-2022:draftedTRUE 7.396e+01
## positionF:season2021-2022:draftedTRUE -2.620e+01
## treatmentPlayed:plyr_quality:draftedTRUE 2.187e-11
## positionF:plyr_quality:draftedTRUE -7.807e-10
## season2021-2022:plyr_quality:draftedTRUE -2.157e+02
## treatmentPlayed:age:draftedTRUE 1.784e-11
## positionF:age:draftedTRUE -6.889e-12
## season2021-2022:age:draftedTRUE -1.656e+00
## plyr_quality:age:draftedTRUE -4.583e-11
## treatmentPlayed:positionF:season2021-2022:plyr_quality 3.691e+00
## treatmentPlayed:positionF:season2021-2022:age -4.154e-01
## treatmentPlayed:positionF:plyr_quality:age 2.860e-12
## treatmentPlayed:season2021-2022:plyr_quality:age 1.771e-01
## positionF:season2021-2022:plyr_quality:age -1.260e-01
## treatmentPlayed:positionF:season2021-2022:draftedTRUE -9.045e+01
## treatmentPlayed:positionF:plyr_quality:draftedTRUE 9.010e-13
## treatmentPlayed:season2021-2022:plyr_quality:draftedTRUE 1.144e+01
## positionF:season2021-2022:plyr_quality:draftedTRUE 2.067e+02
## treatmentPlayed:positionF:age:draftedTRUE -1.712e-11
## treatmentPlayed:season2021-2022:age:draftedTRUE -3.864e+00
## positionF:season2021-2022:age:draftedTRUE 1.404e+00
## treatmentPlayed:plyr_quality:age:draftedTRUE -1.306e-12
## positionF:plyr_quality:age:draftedTRUE 4.600e-11
## season2021-2022:plyr_quality:age:draftedTRUE 1.141e+01
## treatmentPlayed:positionF:season2021-2022:plyr_quality:age -1.731e-01
## treatmentPlayed:positionF:season2021-2022:plyr_quality:draftedTRUE 1.911e-01
## treatmentPlayed:positionF:season2021-2022:age:draftedTRUE 4.763e+00
## treatmentPlayed:positionF:plyr_quality:age:draftedTRUE NA
## treatmentPlayed:season2021-2022:plyr_quality:age:draftedTRUE -6.749e-01
## positionF:season2021-2022:plyr_quality:age:draftedTRUE -1.095e+01
## treatmentPlayed:positionF:season2021-2022:plyr_quality:age:draftedTRUE NA
## Std. Error
## (Intercept) 8.116e-01
## treatmentPlayed 2.074e+00
## positionF 1.066e+00
## season2021-2022 1.216e+00
## plyr_quality 3.233e+00
## age 4.683e-02
## draftedTRUE 1.946e+01
## treatmentPlayed:positionF 5.840e+00
## treatmentPlayed:season2021-2022 3.107e+00
## positionF:season2021-2022 1.597e+00
## treatmentPlayed:plyr_quality 7.196e+00
## positionF:plyr_quality 3.528e+00
## season2021-2022:plyr_quality 4.833e+00
## treatmentPlayed:age 1.197e-01
## positionF:age 6.194e-02
## season2021-2022:age 6.623e-02
## plyr_quality:age 1.800e-01
## treatmentPlayed:draftedTRUE 4.772e+01
## positionF:draftedTRUE 1.967e+01
## season2021-2022:draftedTRUE 2.918e+01
## plyr_quality:draftedTRUE 1.307e+02
## age:draftedTRUE 1.146e+00
## treatmentPlayed:positionF:season2021-2022 8.753e+00
## treatmentPlayed:positionF:plyr_quality 1.077e+01
## treatmentPlayed:season2021-2022:plyr_quality 1.075e+01
## positionF:season2021-2022:plyr_quality 5.276e+00
## treatmentPlayed:positionF:age 3.406e-01
## treatmentPlayed:season2021-2022:age 1.693e-01
## positionF:season2021-2022:age 8.760e-02
## treatmentPlayed:plyr_quality:age 3.942e-01
## positionF:plyr_quality:age 1.973e-01
## season2021-2022:plyr_quality:age 2.545e-01
## treatmentPlayed:positionF:draftedTRUE 4.752e+01
## treatmentPlayed:season2021-2022:draftedTRUE 7.157e+01
## positionF:season2021-2022:draftedTRUE 2.951e+01
## treatmentPlayed:plyr_quality:draftedTRUE 1.070e+01
## positionF:plyr_quality:draftedTRUE 1.308e+02
## season2021-2022:plyr_quality:draftedTRUE 1.960e+02
## treatmentPlayed:age:draftedTRUE 2.805e+00
## positionF:age:draftedTRUE 1.159e+00
## season2021-2022:age:draftedTRUE 1.621e+00
## plyr_quality:age:draftedTRUE 7.712e+00
## treatmentPlayed:positionF:season2021-2022:plyr_quality 1.612e+01
## treatmentPlayed:positionF:season2021-2022:age 4.817e-01
## treatmentPlayed:positionF:plyr_quality:age 6.081e-01
## treatmentPlayed:season2021-2022:plyr_quality:age 5.575e-01
## positionF:season2021-2022:plyr_quality:age 2.791e-01
## treatmentPlayed:positionF:season2021-2022:draftedTRUE 7.126e+01
## treatmentPlayed:positionF:plyr_quality:draftedTRUE 2.061e+00
## treatmentPlayed:season2021-2022:plyr_quality:draftedTRUE 1.601e+01
## positionF:season2021-2022:plyr_quality:draftedTRUE 1.961e+02
## treatmentPlayed:positionF:age:draftedTRUE 2.793e+00
## treatmentPlayed:season2021-2022:age:draftedTRUE 3.967e+00
## positionF:season2021-2022:age:draftedTRUE 1.639e+00
## treatmentPlayed:plyr_quality:age:draftedTRUE 6.183e-01
## positionF:plyr_quality:age:draftedTRUE 7.719e+00
## season2021-2022:plyr_quality:age:draftedTRUE 1.091e+01
## treatmentPlayed:positionF:season2021-2022:plyr_quality:age 8.600e-01
## treatmentPlayed:positionF:season2021-2022:plyr_quality:draftedTRUE 2.914e+00
## treatmentPlayed:positionF:season2021-2022:age:draftedTRUE 3.950e+00
## treatmentPlayed:positionF:plyr_quality:age:draftedTRUE NA
## treatmentPlayed:season2021-2022:plyr_quality:age:draftedTRUE 8.744e-01
## positionF:season2021-2022:plyr_quality:age:draftedTRUE 1.092e+01
## treatmentPlayed:positionF:season2021-2022:plyr_quality:age:draftedTRUE NA
## t value
## (Intercept) 0.000
## treatmentPlayed 0.000
## positionF 0.000
## season2021-2022 1.776
## plyr_quality 0.309
## age 0.000
## draftedTRUE 0.000
## treatmentPlayed:positionF 0.000
## treatmentPlayed:season2021-2022 -0.499
## positionF:season2021-2022 0.021
## treatmentPlayed:plyr_quality 0.000
## positionF:plyr_quality 0.000
## season2021-2022:plyr_quality -0.940
## treatmentPlayed:age 0.000
## positionF:age 0.000
## season2021-2022:age -1.524
## plyr_quality:age 0.000
## treatmentPlayed:draftedTRUE 0.000
## positionF:draftedTRUE 0.000
## season2021-2022:draftedTRUE 1.074
## plyr_quality:draftedTRUE 0.000
## age:draftedTRUE 0.000
## treatmentPlayed:positionF:season2021-2022 0.930
## treatmentPlayed:positionF:plyr_quality 0.000
## treatmentPlayed:season2021-2022:plyr_quality -0.319
## positionF:season2021-2022:plyr_quality 0.486
## treatmentPlayed:positionF:age 0.000
## treatmentPlayed:season2021-2022:age 0.440
## positionF:season2021-2022:age 0.046
## treatmentPlayed:plyr_quality:age 0.000
## positionF:plyr_quality:age 0.000
## season2021-2022:plyr_quality:age 0.892
## treatmentPlayed:positionF:draftedTRUE 0.000
## treatmentPlayed:season2021-2022:draftedTRUE 1.033
## positionF:season2021-2022:draftedTRUE -0.888
## treatmentPlayed:plyr_quality:draftedTRUE 0.000
## positionF:plyr_quality:draftedTRUE 0.000
## season2021-2022:plyr_quality:draftedTRUE -1.101
## treatmentPlayed:age:draftedTRUE 0.000
## positionF:age:draftedTRUE 0.000
## season2021-2022:age:draftedTRUE -1.021
## plyr_quality:age:draftedTRUE 0.000
## treatmentPlayed:positionF:season2021-2022:plyr_quality 0.229
## treatmentPlayed:positionF:season2021-2022:age -0.862
## treatmentPlayed:positionF:plyr_quality:age 0.000
## treatmentPlayed:season2021-2022:plyr_quality:age 0.318
## positionF:season2021-2022:plyr_quality:age -0.452
## treatmentPlayed:positionF:season2021-2022:draftedTRUE -1.269
## treatmentPlayed:positionF:plyr_quality:draftedTRUE 0.000
## treatmentPlayed:season2021-2022:plyr_quality:draftedTRUE 0.714
## positionF:season2021-2022:plyr_quality:draftedTRUE 1.054
## treatmentPlayed:positionF:age:draftedTRUE 0.000
## treatmentPlayed:season2021-2022:age:draftedTRUE -0.974
## positionF:season2021-2022:age:draftedTRUE 0.856
## treatmentPlayed:plyr_quality:age:draftedTRUE 0.000
## positionF:plyr_quality:age:draftedTRUE 0.000
## season2021-2022:plyr_quality:age:draftedTRUE 1.046
## treatmentPlayed:positionF:season2021-2022:plyr_quality:age -0.201
## treatmentPlayed:positionF:season2021-2022:plyr_quality:draftedTRUE 0.066
## treatmentPlayed:positionF:season2021-2022:age:draftedTRUE 1.206
## treatmentPlayed:positionF:plyr_quality:age:draftedTRUE NA
## treatmentPlayed:season2021-2022:plyr_quality:age:draftedTRUE -0.772
## positionF:season2021-2022:plyr_quality:age:draftedTRUE -1.003
## treatmentPlayed:positionF:season2021-2022:plyr_quality:age:draftedTRUE NA
## Pr(>|t|)
## (Intercept) 1.0000
## treatmentPlayed 1.0000
## positionF 1.0000
## season2021-2022 0.0766
## plyr_quality 0.7572
## age 1.0000
## draftedTRUE 1.0000
## treatmentPlayed:positionF 1.0000
## treatmentPlayed:season2021-2022 0.6179
## positionF:season2021-2022 0.9830
## treatmentPlayed:plyr_quality 1.0000
## positionF:plyr_quality 1.0000
## season2021-2022:plyr_quality 0.3478
## treatmentPlayed:age 1.0000
## positionF:age 1.0000
## season2021-2022:age 0.1284
## plyr_quality:age 1.0000
## treatmentPlayed:draftedTRUE 1.0000
## positionF:draftedTRUE 1.0000
## season2021-2022:draftedTRUE 0.2837
## plyr_quality:draftedTRUE 1.0000
## age:draftedTRUE 1.0000
## treatmentPlayed:positionF:season2021-2022 0.3532
## treatmentPlayed:positionF:plyr_quality 1.0000
## treatmentPlayed:season2021-2022:plyr_quality 0.7502
## positionF:season2021-2022:plyr_quality 0.6271
## treatmentPlayed:positionF:age 1.0000
## treatmentPlayed:season2021-2022:age 0.6603
## positionF:season2021-2022:age 0.9637
## treatmentPlayed:plyr_quality:age 1.0000
## positionF:plyr_quality:age 1.0000
## season2021-2022:plyr_quality:age 0.3730
## treatmentPlayed:positionF:draftedTRUE 1.0000
## treatmentPlayed:season2021-2022:draftedTRUE 0.3021
## positionF:season2021-2022:draftedTRUE 0.3752
## treatmentPlayed:plyr_quality:draftedTRUE 1.0000
## positionF:plyr_quality:draftedTRUE 1.0000
## season2021-2022:plyr_quality:draftedTRUE 0.2718
## treatmentPlayed:age:draftedTRUE 1.0000
## positionF:age:draftedTRUE 1.0000
## season2021-2022:age:draftedTRUE 0.3078
## plyr_quality:age:draftedTRUE 1.0000
## treatmentPlayed:positionF:season2021-2022:plyr_quality 0.8190
## treatmentPlayed:positionF:season2021-2022:age 0.3890
## treatmentPlayed:positionF:plyr_quality:age 1.0000
## treatmentPlayed:season2021-2022:plyr_quality:age 0.7510
## positionF:season2021-2022:plyr_quality:age 0.6518
## treatmentPlayed:positionF:season2021-2022:draftedTRUE 0.2052
## treatmentPlayed:positionF:plyr_quality:draftedTRUE 1.0000
## treatmentPlayed:season2021-2022:plyr_quality:draftedTRUE 0.4755
## positionF:season2021-2022:plyr_quality:draftedTRUE 0.2927
## treatmentPlayed:positionF:age:draftedTRUE 1.0000
## treatmentPlayed:season2021-2022:age:draftedTRUE 0.3307
## positionF:season2021-2022:age:draftedTRUE 0.3924
## treatmentPlayed:plyr_quality:age:draftedTRUE 1.0000
## positionF:plyr_quality:age:draftedTRUE 1.0000
## season2021-2022:plyr_quality:age:draftedTRUE 0.2961
## treatmentPlayed:positionF:season2021-2022:plyr_quality:age 0.8406
## treatmentPlayed:positionF:season2021-2022:plyr_quality:draftedTRUE 0.9478
## treatmentPlayed:positionF:season2021-2022:age:draftedTRUE 0.2287
## treatmentPlayed:positionF:plyr_quality:age:draftedTRUE NA
## treatmentPlayed:season2021-2022:plyr_quality:age:draftedTRUE 0.4407
## positionF:season2021-2022:plyr_quality:age:draftedTRUE 0.3164
## treatmentPlayed:positionF:season2021-2022:plyr_quality:age:draftedTRUE NA
##
## (Intercept)
## treatmentPlayed
## positionF
## season2021-2022 .
## plyr_quality
## age
## draftedTRUE
## treatmentPlayed:positionF
## treatmentPlayed:season2021-2022
## positionF:season2021-2022
## treatmentPlayed:plyr_quality
## positionF:plyr_quality
## season2021-2022:plyr_quality
## treatmentPlayed:age
## positionF:age
## season2021-2022:age
## plyr_quality:age
## treatmentPlayed:draftedTRUE
## positionF:draftedTRUE
## season2021-2022:draftedTRUE
## plyr_quality:draftedTRUE
## age:draftedTRUE
## treatmentPlayed:positionF:season2021-2022
## treatmentPlayed:positionF:plyr_quality
## treatmentPlayed:season2021-2022:plyr_quality
## positionF:season2021-2022:plyr_quality
## treatmentPlayed:positionF:age
## treatmentPlayed:season2021-2022:age
## positionF:season2021-2022:age
## treatmentPlayed:plyr_quality:age
## positionF:plyr_quality:age
## season2021-2022:plyr_quality:age
## treatmentPlayed:positionF:draftedTRUE
## treatmentPlayed:season2021-2022:draftedTRUE
## positionF:season2021-2022:draftedTRUE
## treatmentPlayed:plyr_quality:draftedTRUE
## positionF:plyr_quality:draftedTRUE
## season2021-2022:plyr_quality:draftedTRUE
## treatmentPlayed:age:draftedTRUE
## positionF:age:draftedTRUE
## season2021-2022:age:draftedTRUE
## plyr_quality:age:draftedTRUE
## treatmentPlayed:positionF:season2021-2022:plyr_quality
## treatmentPlayed:positionF:season2021-2022:age
## treatmentPlayed:positionF:plyr_quality:age
## treatmentPlayed:season2021-2022:plyr_quality:age
## positionF:season2021-2022:plyr_quality:age
## treatmentPlayed:positionF:season2021-2022:draftedTRUE
## treatmentPlayed:positionF:plyr_quality:draftedTRUE
## treatmentPlayed:season2021-2022:plyr_quality:draftedTRUE
## positionF:season2021-2022:plyr_quality:draftedTRUE
## treatmentPlayed:positionF:age:draftedTRUE
## treatmentPlayed:season2021-2022:age:draftedTRUE
## positionF:season2021-2022:age:draftedTRUE
## treatmentPlayed:plyr_quality:age:draftedTRUE
## positionF:plyr_quality:age:draftedTRUE
## season2021-2022:plyr_quality:age:draftedTRUE
## treatmentPlayed:positionF:season2021-2022:plyr_quality:age
## treatmentPlayed:positionF:season2021-2022:plyr_quality:draftedTRUE
## treatmentPlayed:positionF:season2021-2022:age:draftedTRUE
## treatmentPlayed:positionF:plyr_quality:age:draftedTRUE
## treatmentPlayed:season2021-2022:plyr_quality:age:draftedTRUE
## positionF:season2021-2022:plyr_quality:age:draftedTRUE
## treatmentPlayed:positionF:season2021-2022:plyr_quality:age:draftedTRUE
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## Residual standard error: 0.1901 on 376 degrees of freedom
## Multiple R-squared: 0.7775, Adjusted R-squared: 0.7414
## F-statistic: 21.54 on 61 and 376 DF, p-value: < 2.2e-16
## Warning: not plotting observations with leverage one:
## 15, 16
…